immunodiagnostic /-dī′əgnos″tik/ [L, immunis + Gk, dia, through, gnosis knowledge] , pertaining to or characterizing a diagnosis based on an antigen-antibody reaction. In many cases a tumor releases a discrete antigenic substance into the blood. Detection of a particular antigen can provide an immunodiagnostic sign of the presence of the tumor associated with that antigen.
